The 1968 Ignition Switch problem

[metalblessing]

Hello, this is my first post here so thanks for having me. I recently acquired a 1968 Cadillac Hearse and am slowly working on restoring it. I have been having intermittent issues with the throttle cutting out for months now and I only recently learned that 1968 was known for a shorting ignition switch that would melt.

The hearses were the same as other Cadillac models from the dash forward so it shouldnt be much different from a fleetwood as far as the ignition goes.

With that said, has anyone seen improvement upon converting the ignition switch to an aftermarket one that will not melt? And if so what do you recommend? I am considering instead of spending $465 on an original part, buying something aftermarket and converting it if possible so I can avoid running into this issue again.

Any input would be appreciated.

[TJ Hopland]

I don't have any first hand experience on this issue with a 68 so it will be interesting to hear from others if that is really a thing or not.    I also have limited experience with the professional cars but the couple I worked on were far from stock up front especially when it came to electrical.   At least yours being a hearse didn't add a ton of electrical like an ambulance did so that should help. 

If it is a thing and you replace it with an original perhaps setting it up with a relay or two would be a good idea to take some of the load off the switch.  I think people like Painless make some universal relay distribution blocks that would make things a bit easier. 

[metalblessing]

I don't have any first hand experience on this issue with a 68 so it will be interesting to hear from others if that is really a thing or not.    I also have limited experience with the professional cars but the couple I worked on were far from stock up front especially when it came to electrical.   At least yours being a hearse didn't add a ton of electrical like an ambulance did so that should help. 

If it is a thing and you replace it with an original perhaps setting it up with a relay or two would be a good idea to take some of the load off the switch.  I think people like Painless make some universal relay distribution blocks that would make things a bit easier.

Well its not a full-fledged ambulance, its what the called a "combination vehicle". Interchanges to a hearse or ambulance as needed. Does have a light on top, but it uses the same 472 engine, switch, etc as other 68 cadillacs.

[Highwayman68]

Please provide more details on what you are describing as the throttle cutting out.

What exactly is happening?
Is it only with the car in motion or both in motion and sitting still or only when sitting still?
Is the ignition key assembly getting hot?
How do the wires connected to the ignition switch on the back look, any signs of melting or heat stress?
Does shifting gears have any effect on the problem happening?
Does the engine immediately restart after the issue occurs?

[metalblessing]

I am still learning how to work on some of this stuff so forgive me.

During normal driving occasionally the issue will crop up where while in motion I press the accelerator and the for a second it will accelerate as it should but then the motor just cuts out. If I continue holding the gas the engine will completely stop, but even after the engine stops, if I let go of the accelerator altogether it starts back up on its own.

Sometimes when trying to start the car the lights all work but the car does not turn over at all with a full battery. Usually putting it in gear and back to park will allow me to start it.

I am unsure how the wires look, but it do see some stripping marks on the ignition on the dash so it looks like someone has tampered with it or replaced it in the past.

And yes if the car does fully stall it starts right back up at the turn of a key.

I had initially thought I had a clogged fuel line, but I have several others telling me this was common for 1968 and it is a good chance I have a bad ignition switch.

I will check the temperature of the assembly next time I encounter it. It tends to only start happening on my longer drives, and get progressively worse

[35-709]

"Sometimes when trying to start the car the lights all work but the car does not turn over at all with a full battery. Usually putting it in gear and back to park will allow me to start it."

That sounds like the neutral safety switch is slightly out of adjustment.

"It tends to only start happening on my longer drives, and get progressively worse"

And that sounds like a good place to start would be to change your fuel filter.

My 2 cents.

[bcroe]

Any commercial car is likely to have more electrical loads,
increasing the chance of failures.  if your ign switch has failed
you will probably need to replace it.  To prevent more
failures of that type, its common practice to add a relay
or several that actually switch the loads.  The ign switch output
is then wired so it only drives the relay coils, or a much
smaller fraction of the load.  Bruce Roe

[Highwayman68]

We are all here to help so ask the questions and take the answers as we are there with you trying to figure it out.

It does sound like one of two items or possibly both. The ignition switch on the dash and/or the Neutral Safety switch at the base of the steering column.

The ignition switch is probably the first place to start. My switch is an original and I have never had any issues with it. Nor have I ever heard of there being a known issue with the switches, others on here may have and can help confirm this. These are easy to change according to the manual. We can provide some guidance on how to do this if you need it.

Do you ever have trouble starting the car and find that moving the gear shifter helps it start? This will help identify if the Neutral Safety switch is involved.

[bcroe]

The neutral safety switch has nothing to do with the car cutting
out.  But it controls the starter.  I take the shift lever in neutral
and move it slightly, testing the starter to see if there is an
improper position where the starter won't work.  An adjustment
of switch position should get the operating range in the center of
the lever neutral position, hopefully this will also center the PARK
position of starter operation.  Bruce Roe

[Glen]

There is a wire harness that comes up from the starter.  In that harness is a connector.  Check that connector.  My 68 ELDO had a similar problem.  When accelerating the engine would cut out.  But as the engine lost power it would come back on, then cut out again.  The connector body was partly melted and the red wire which carries most of the power from the starter to the rest of the car was separating at the connector as the engine moved from acceleration.  As it moved back to the at rest position the wire reconnected.     

[bcroe]

There is a wire harness that comes up from the starter.  In that harness is a connector.  Check that connector.  My 68 ELDO had a similar problem.  When accelerating the engine would cut out.  But as the engine lost power it would come back on, then cut out again.  The connector body was partly melted and the red wire which carries most of the power from the starter to the rest of the car was separating at the connector as the engine moved from acceleration.  As it moved back to the at rest position the wire reconnected.   

That arrangement was thought up by some UN engineer (bean counter)
who wanted to save a few pennies, reducing the reliability and general
quality of that and so many other cars.  Unrelated car wiring is routed
down to the hot, wet, motion prone starter main terminal, so that a
main terminal isn't required near the battery.  It also makes it a lot
harder to work on the starter. 

But my 62 wasn't done that way, the big bat cable first went to a big
terminal on the dryer, cooler, motion free fender, THEN it continued
down with one other wire to the starter.  I have converted every car
here to my 62 arrangement, here it is on my 77.  This is also an
opportunity to insert some fusible links to main feeds, that may
not have been used on older models.  That might have prevented
the wiring fire I had earlier in my 64.  Bruce Roe

[metalblessing]

 I have jumped into this without a great deal of knowledge with working on cars. I've managed to change spark plugs and replace plug wires and thats the most complicated work ive done so far. I am try to learn though, I generally have trouble locating things in the engine bay though.

I will see if I can locate the starter and find that harness and check it. I've checked online and it looks like the OEM ignition switches run about $465. I still havent bought a shop manual yet but its on my list.

Yes I do occasionally have to move the gear shifter to get it to start. took me awhile to connect the dots there.

When I first got the car I made the mistake of paying a local shop to do about 3k worth or work. Now I cant afford to fix anything hardly.

On top of this car being driven a few times a year before I bought it, I'm pretty sure it was run on ethanol. So Im trying to burn up my last quarter tank of ethanol so i can switch to non-ethanol gas. I know that ethanol is bad news.

[Scot Minesinger]

Geoff has your answer (35-709), neutral safety switch and ignition.  It could also be the red wire on starter getting disconnect on full throttle acceleration.  Check your motor mounts.

Get the shop manual, it is $35 or so on e-bay and well worth it.

Yes many of us made the mistake of hiring a local mechanic to do some work incorrectly and suffer overcharges.  Hence we all became our own best mechanics.  I used to be a spark plug changer, and now out of necessity for quality work I'm pulling engines, restoring suspensions, repairing climate controls, replacing wiring harnesses and the like.

If you can read and take your time, your work will be way better than a local shop not accustomed to working on older cars.

Good luck,

Scot

[cadillacmike68]

Needing to fiddle & diddle with the gear selector occasionally is definitely a neutral safety adjustment switch issue. Be careful, they are easy to break.

As for cutting out when accelerating, if your motor mounts are worn, the engine will move quite a bit more. You can see this for yourself by sharply moving the throttle rod yourself in the engine bay with the engine running. Look at how much the engine tilts. These engines are Heavy and they wear out mounts.

As for the ignition switch, Highwayman has had his 1968 for some 30+ years and I've had mine for 20 years, and no issues with the ignition switch (at least Mark hasn't mentioned any). It's actually more robust than 1969 & later, especially on cars with T&T columns, because the switch is in the dash.

[bcroe]

Get the shop manual, it is $35 or so on e-bay and well worth it.

Yes many of us made the mistake of hiring a local mechanic to do some work incorrectly and suffer overcharges.  Hence we all became our own best mechanics.  I used to be a spark plug changer, and now out of necessity for quality work I'm pulling engines, restoring suspensions, repairing climate controls, replacing wiring harnesses and the like.

If you can read and take your time, your work will be way better than a local shop not accustomed to working on older cars.
Good luck,
Scot     

I have taken the same path as Scot, driven by the twin needs of top quality
and economy.  This makes practical an extensive preventative maintenance
program.  Convenience comes into the picture, my place, my time.  Tools
and manuals are needed, usually they pay for themselves during the first use. 

As a lifetime designer, I have taken things farther.  Some things are modified
to ease maintenance as much as possible, and obvious weak points are
designed out completely when possible.  I really drive my cars.  Bruce Roe

[metalblessing]

Needing to fiddle & diddle with the gear selector occasionally is definitely a neutral safety adjustment switch issue. Be careful, they are easy to break.

As for cutting out when accelerating, if your motor mounts are worn, the engine will move quite a bit more. You can see this for yourself by sharply moving the throttle rod yourself in the engine bay with the engine running. Look at how much the engine tilts. These engines are Heavy and they wear out mounts.

As for the ignition switch, Highwayman has had his 1968 for some 30+ years and I've had mine for 20 years, and no issues with the ignition switch (at least Mark hasn't mentioned any). It's actually more robust than 1969 & later, especially on cars with T&T columns, because the switch is in the dash.

Yeah, when I first start the engine while its warming up it shakes quite a bit, once it warmed up though it is a bit smoother. Seafoam helped reduce the shaking a bit but sounds for sure like the mounts are loose or something.

[metalblessing]

If I do have to replace motor mounts I will likely need to pay someone. I dont have the equipment for it. You all have added to my list of things to check this weekend though, so thanks for that. I will report back on these things next week if I have enough time on the weekend to check these

[cadillacmike68]

Blake, that's either a carbie issue or valve issue with the rough cold idling. Once it warms up and smooths out, open the hood, get in there and sharply pull / push (I think its Push back) on the throttle rod and watch the engine. It will cant to the right as you are looking at it. Too much and the mounts are worn.

Get underneath it and look at how much clearance is between the AC pulleys and the frame. There should be 2-3 fingers clearance. A sure sign of worn mounts it that it's a REAL PITA to get those belts off, because they won't clear the pulley flanges.

If you need mounts get them at rockauto.com, NOT OPGI. Less expensive and the OPGI ones I got a fer years ago had POOR quality control.

[Highwayman68]

Here is a cheap option to test if your switch is the culprit

https://www.ebay.com/itm/1946-1968-Cadillac-Ignition-Switch-Universal-complete-with-keys/222847203065?hash=item33e2ba76f9:g:PPUAAOSw0UdXqecP

[metalblessing]

Here is a cheap option to test if your switch is the culprit

https://www.ebay.com/itm/1946-1968-Cadillac-Ignition-Switch-Universal-complete-with-keys/222847203065?hash=item33e2ba76f9:g:PPUAAOSw0UdXqecP

Ah link explains a bit. Thats why my igniton key looks like some kinda lockbox key. I bet a previous owner installed this exact one.